Fuel injector



Patented Mar. 10, 1953 UNITED PATENT '-O.'F FZICE FUEL INJECTOR --William 'Mashinter, Chicago, Ill., assignorfof wnine teen per cent to MargeryflDJ McCormick and Alan G. 'McCormick, bothof ChicagmfIll.

'flri'ginal' application May :29, 194A, eSe'rial'cNo.

537 -793. ."Divided and this applications'Novemv GCl'airhs.

1 This invention pertains to; pump mechanism, injector mechanism or atomizing mechanism adapted to either supply-1 solidliq-uid or spray comminuted fluid; ormixtures :of fluid and solid.

the fiuiddelivered to thetinjecting means.

"Witli'these aridQv'ariousother objects in view,

Fuel injection pumps-as heretofore designed 5 theinvention may consist of certainnovelifeacommonly include a plunger -working in a cylintures of construction ;and" operation .as will 'be der and intermittently acttuatedto deliver measmore" fully jd'escribedl; arid Vjparticularly pointed ured quantities of- "fuels-to theengine, }'Beeause out in ithez' specific'ation, drawings and-claims of the high fuel pressures-ordinarily involved, a appended hereto. I very close-fit between...plunger and cylinder is Inthedrawingsywhichillustrateembodiments required for successfuloperation and a 'leakof the'device' and wherein like reference characproof fit-is extremely: 'difiicult toohtainfland imters are used to designatelike, parts- 7 possible to maintain, particularly. when using L'Figure lis ai'sect'ional view-eta modified form light fuels, such as: gasoline-having little or no of pump and nozzle adapted to-be actuated by lubricating. properties. engine cylinder pressure" of the cylinder-tobe One object oflthepresent invention is toprosupplidjby the'nofzzle; I

i vide a V substantially} leak p'roof "fuel injection Figure 2 is amodified form'of inj'ector adapted pump. to vbe actuatedby'pressureof-the cylinder to--be Another object is to; provide a fuel'inJection upp ed by" d 8 3and, pump that issubstantially'linimune' to leakage Figuredis-258 0 modified producing wear. form of injection system'--'wherein the injector Another object is to; provide an improved belmay be-operated'by-the suction from the cylinder lows type .of pump/capable of withstanding high supplied by; the fueltherefrom,== or per'ated by pressures .over long periods oil-use. an adjacent-cylinder, or-wherein-the injector may Anotherobject is to' combine, a bellows type pply l t0 a intake m f of pump anda fuel injection nozzle into a unitary aDD S *d oflapplication structure. Serial No} 537,793 filed May 29, 1944, now J Patent Another object is to provide'a fuel injection P 5 3 ve ber 1451950- nozzle having aselfec ont'ained bellows type of Rferring filfst of alP-to themodificationilluspump and a loaded'discharge valve responsive to a 'l v v F el i midjec r th pressure the pump. 'trated" w-hich -is adapted for cylinder 111180171011 Another objectis to, provide a pump fed'fuel *Wherein-the compression pressure of: the cylinder injection nozzle having as elf-r-cleaning discharge l utilized-"150 Q itheinjwtori'fol" Va1ve plying fuel-to the cylindemto which the injec'tor Another object is toprovide a combined fuels -g mi d- Theinjecmr-compri he-n zzle pump and injection. nozzle. of improved, simple fizhavmg' threadedl'engagement"as and inexpensive design end ofthecasirig or housing 86, a seal- 131 being Another object of the invention is, to provide "intermsewbetwnitheinozzle andcasingmpre" pump mechanism: so constructed-and arranged Vent ak ge 'P YQbQWW J that it may be used to pump solid-liquid. 4O The 1 2 "9 1 a housmg Another object of the invention is to provide t f fm theend Seal p a pump for supplying fluidcunder pressureland fis C l B YIQ m d With a in measured quantities to means forutilizing the Suitably s ap d h ad-92 for facilitatingasseinblysupplied fluid, as where fuel is-sprayed into the The 0 l 0 i fn f threaded as @1196 for cylinder of an engine or where other. liquidsueh receiving ccmplementarythreads ofthe-throttle as Water, is sprayed into such. cylinder forv power "Screw b il fp ovided with means or antidetonating. reasons, such as a lever 98for' rotatingthe screw to there- Another object is to -provideinjecting-means l y' o c w in f yfw by- Stroke for supplying fuel-to an internal combustion en- 0f the i ect r"i con blled. v H gine which may be used with manifold or sepat e E T DICE m t the bore rate cylinder injection and whereinthe fuel is 15 0 throughwhi hl h tubular,up ex ns n introduced in-properly atomized condition over M2 of the ibellowsfltopfseal I04 jextends. The the entire range of'operation of theengine, i, e., tubular extension M12 "is pr'ovided with the regardless of theoperatingspeed ofithe engine. isprifiglprjessedichecl; valvelfifi opening toward lAnother-objectofethezinvention istop'rbvide -55'the top seal 1Miand'the'extension"I02 'isia'dapted to be connected to a suitable source of fuel supply from which fuel may be supplied under pressure to the extension I02, or the device may operate as its own pump from the source of supply. The top seal I04 is secured between the cap 88 and the shoulder I88 provided on the casing 86 and suitable sealing means may be provided between the top seal and said shoulder,

The top seal is provided with spaced slots IIO through which upstanding fingers N2 of the aligning sleeve II4 extends, said fingers being adapted to abut against the throttle screw 86 for movement thereby. The top seal I04 is provided with the spaced concentric outer and inner rims I I6 and H8 to which the upper ends of the bellows I20 and I22 are respectively connected in a leakproof manner, the lower ends of said bellows being similarly secured to the concentric outer and inner spaced rims I24 and I26 respectively of the intermediate seal 528. The seal I28 is provided with the oppositely extending rim I30 to which the upper end of the bellows I32 is connected in a leakproof manner, the lower end of said bellows being similarly connected to the upwardly extending rim I34 of the lower seal I36. The seal I36 is fixedly secured between the nozzle 82 and the casing 85.

The nozzle 82 is provided with the bore I38 terminating in the valve seat I40 on which the injection valve I42 is adapted to seat, the valve and seat being so constructed and arranged that the fuel passing through the bore past the valve will be sprayed. The valve I42 is provided with the stem I44 having a spring seat I46 thereon, a spring I48 being disposed between said seat and the nozzle for normally urging the valve I42 to closed position, the stem being cut out as at 150 for permitting passage of fuel past the stem. In cutting out the stem I44, it is preferable that th portion I52 of the stem is circular in section while the portions I54 of the cut-out are so arranged that they form lands or guiding means for the valve I42 to insure that said valve always seats properly. I V

The nozzle 82 is provided with the communicating bores I56 and I58communicating with the valve seat I80 provided on the casing 88, the valve seat I60 communicating with the bore I82 extending upwardly and communicating with the chamber I84 formed between the casing 88 and the bellows I20. Valve I86 is provided with the valve stem I68 extending upwardly into the chamber I64 to be engaged by the seal I28, said stem being provided with the spring seat I70 on which the upper end of the spring I12 is seated, the lower end of the spring I'I2 being seated on the shoulder I14 provided in the casing 86 within the bore I62.

The top seal I04 is provided with the depending lower tubular extension IIt extending downwardly to a point adjacent the valve stem I44 whereby when fuel or other fluid is supplied, a cooling action will take place as the relatively cool, newly supplied fuel is introduced at a low point in the nozzle, that is, at the point subjected to the highest temperature.

In operation of this form of the device, assuming that the nozzle is applied to the cylinder of an internal combustion engine, and assuming that valve I42 is closed and the pressure within the bellows I32 and I22 is equal to supply pressure, the pressure within the chamber I84 is the same pressure as that in the engine cylinder, inasmuch as the valve IE6 is open. The piston of the cylinder on its compression stroke will then cause a rise in pressure in the chamber I84 causing upward movement of the seal I28, compressing the bellows I20 and I22, which in turn elongates the bellows I32 supplying fuel to the valve I42 under pressure. When the pressure reaches a predetermined amount, valve I42 will be caused to open against the spring I48 permitting injection of the fuel into the cylinder.

Upward movement of the seal I28 will permit the spring I'i2 and compression pressure to urge the valve I68 towards closed position, and the spring I48 and compression pressure will urge valve I42 toward closed position, so that both valves I42 and IE8 are closed during the firing of the fuel in the cylinder. Upward movement of the seal I28 is controlled by the position of the throttle screw 98, that is, the seal I28 will be caused to move upwardly by the engine compression until the fingers II2 of sleeve II4 engage the screw 88.

On the exhaust stroke the products of combustion will be removed from the cylinder with a consequent decrease in pressure. At a predetermined position of the piston, the pressure within the cylinder will be less than the pressure in the chamber IE4 at which point the valve I86 will open with a consequent reduction in pressure in the chamber I84. This occurs at the time the seal I28 moves downwardly toward a position where the bellows are restored to their normal position and the valve IE8 is open. In this position the injector is in position to repeat the cycle of operation.

In the construction illustrated in Figure 2, the injector comprises nozzle I18 connected as through threads I to the casing or housing I82. The casing is connected as through the threads I84 to the end head I88. The end head is provided with the threads I88 for reception of complementary threads of the throttle screw I90, said throttle screw I98 being provided with operating means such as the lever I92 whereby movement of the lever to rotate the screw I causes reciprocation of the screw. The screw is adapted to abut and control the movement of the inner bellows top seal I94 through the projection I98 provided on the seal I94.

The seal 54 is provided with the downwardly extending tubular member :98 extending toward the nozzle Ill? and terminating adjacent the valve stem 208. The valve stem 280 is provided with the spring seat 202 forming the upper seat for one end of the spring 284, the lower end of the spring engaging the seat 288 provided in the nozzle. The valve stem is provided with the cut-out portion 288 terminating in the rounded portion 2I0 disposed adjacent the valve 2I2, the valve seating on the nozzle seat 2M.

The bore 2I8 in projection I88 communicates with bore 2I8 to which the inlet fitting 220 is connected. The fitting 228 is provided with the spring loaded valve 222 adapted to seat toward the source of supply. The fitting extends through a suitable enlarged opening 224 in the head I88 and is movable with respect thereto. Thu fuel supplied through the fitting 220 and bores EIS and 2I8 is introduced to the injector at the hottest point thereof.

The upper end of the inner bellows 22B is secured to the seal I in a leakproof manner and a fixed outer seal 228 is secured between the head I85 and the upper end of the casing I82, and the upper end of the outer bellows 238 is secured to the seal 228 in a leakproof manner. The lower ends of the bellows 228 and 230 are respectively secured to the:concentric upwardly extending flanges 232 and 23 3 of the' intermediate movable casing by means ofthe lock nut 248.

The nozzle H8 is provided with the bore communicating with the'valve bore 252 provided in the casing 182, a spring 254 being interposed between the seal 255, disposed between the casing and the nozzle, and the-valve 258 normally urging the valve to seated position in the seat 2%.

The valve 253 is provided with the upwardly extending stem 262 suitably guided and of a proper configuration to permit passage of fluid past the stem, the stem beingadapted to be engaged-by the seal 2% whereby movement downwardly by the seal opens the valve 258 and movement upwardly of the seal permits the spring 254 to-move the valve toward closed position.

The seal 194 is provided with the outlet-fitting 25 connected back to the source of supply, said fitting passing through the enlarged opening 265 provided in the end head, permitting relative movement between the fitting and the head. The fittingcommunicateswith the bore 268, havin the valve seat 270 adapted to be closed by the valve 212, the valve being urged toward closed position by means of thespring 27M. The valve is provided with the valve stem 2.18 suitably guided as at 2'I8and said stem may likewise be suitably cutawayfor permitting passage of fluid therearound, the stembeing adapted to be engaged-by the seal 23% to move .the. valve 212 to open position. Adjacent the highestpoint of the -bellows 226=an opening: 23lis provided whereby should any air be trapped adjacent the top of the .bellows, itwill beexhausted. by the valve, 218.

In the operation of this form ;of; the device,

. assuming that fuel hasbeen supplied from the source of supply through fitting 22b and. supply pressure isin thebellows 2.26 and 2M and assuming that the nozzle is applied .forcylinder injection on the compression strokethe valve 2 l2 will be closed. Compression pressure will be supplied through bore 25%,;past valve 253 into chamber 282 formed between the bellows230 and the casing E88. .The pressure acting upon the movable seal 236 will cause upward movement thereof, permitting the valve 258 to move toward closed position. Upward movement of the seal; 236 will elongate .the bellow 24d and will cause compression of bellows 22E, causingfuel to be supplied under pressure to the valve 2-i2 in the nozzle until a predetermined pressure causes opening of said valve 212 withthe consequent injection of the fuel. The seal 23% moves upwardly until it engages the stem 276 and continued upward move- ,ment of the seal causes the valve 278 to open,

thereby relieving the fuel pressure in bellows 2M and causing any air or vapor trapped between the bellows 226 and the seal 19d to be exhausted through fitting 26d.

The amount of travel of the seal 236 necessary to open the valve2l2 is controlled by the position of the throttle screw. After, the predetermined amount of fuel has passed the valve 212, it will close. Valve 258 will:remain closedvthat is, the seal 236 will not have opened the valve-during the power stroke and a portion of the exhaust stroke, at which time there will be a-pressure drop in the cylinder and downward movement of the seal 236 will take place by action of the spring. 238 and bellows, causing the-seal to engage the valve stem 282 to move the valve 258-to open position. When open the pressure in the' cylinder and in the chamber will equalize and the device will be in a position to repeat the-cycle.

In the construction illustrated in Figure 3, the injector 5h) consists essentially of thecasing 5l2 secured as at EM-to'the nozzleheadSlG, suitable sealing means 5I3=being provided therebetween. The upper head 52d of' the casing is suitably threaded as I at 522 for 'thereception of the throttle screw 52 i 1 provided-with the throttle means 526. Rotation ofthe throttiemeans 526 causes linear movement of thescrew 524, the end of which project within the casing 5 i2limiting upward movement of-the upper bellows end seal 528 which is preferably of hexishape whereby it is guided in its reciprocatory movement within the cylinder, the cylinder abovethe seal 528 being vented as at 530.

The seal 5283 is fixedly-securedina leakproof manner to the upper end; of. the inner. andv outer bellows 5'32, .534. -A'lower. seal 536 is secured between the nozzle 5H3 andthe shoulder 538 provided-in the casingsuitable sealing means 5% being interposed bet-weentheseal- 536 and nozzle. The lower ends of bellows- 532 and: 534 are fixedly connected in a leakproof manner to the concentric flanges 542 and-5M provided on the lower seal ttd'whei ebya fuel chamber'fi fi and vacuum chamber 548 is formed.

Chamber 5% communicates through bore 550- with the fitting 552 provided with the check valve 55 5 opening toward chamber 546, the fitting 552 being connectedtoa suitable source of fuel supply. Chamber 548 communicates through bore 558 with the pipe 558 which in turn is connected through the valve 550 to the engine cylinder 552, said cylinder being the cylinder supplied by fuelfrom the injector 510 and the cylinder operating said injector, it being understood, of course, that the injector may be supplied with fuel directly from the injector or through a manifold. The valve 560'opens toward the cylinder 5E2, and the nozzleblfi of the injector is provided with the valve seat 564 adapted to seat the valve 566, which is of similarconfiguration to the valve in Figure l, the valve being provided with the'cut away stem 558 and having the spring seat- 5-10 thereon on which the upper end of the spring 572 is seated, the lower end of said spring being seated on the seat bi l.

In operation of this form of the device, suction in cylinder 562 will be transmitted to the chamber 553 between'the bellows causing the seal 528 to move downwardly compressingsaid bellows, causing fuelwithin the chamber 546 to open the valve 556 for supplying themeasured fuel to the cylinderbfiZ. After completion of" the injection, valve 755%) will close dueto the upward movement of the piston cylinder 562' permitting the bellows to return the seal 528 upwardly permitting spring 572 to-close-valve'-556 and drawing fuel through fitting552 into chamber 5 36.

Comparison of load-speedlcontrol of-ina'ectors of known typeandthose illustrated herein "In order to obtain the degreeiofcontrol'over the ratio of air and fuelneededfor-optimum economy and satisfactory performance) that is introduced into an engine cylinder, it is essential that the quantity of fuel per injection be maintained at a fixed ratio with respect to the quantity of air inducted per suction stroke of the engine cylinder.

In a naturally aspirated (not supercharged) internal combustion engine the quantity of air inducted per suction stroke of the engine decreases with increases in engine speed for each and every air throttle position according to the volumetric-efilciency curve (breathing rate) of the engine.

Thus it is evident that if a constant ratio of air and fuel is to be maintained at all times and under all conditions of speeds and loads (loadspeed control), the speed-delivery characteristic of the injection system should conform to the same general form as the volumetric-efiiciency curve of the engine.

In an engine operating on the Otto cycle (such as a gasoline spark-ignition engine) it is necessary to control the air-charge inducted by a throttle control over the air as well as the fuel introduced to the engine. Thus there is a family of volumetric-efiiciency curves (one curve for each throttle position). In the diesel engine, as no air throttle is provided, there is only one volumetric-efficiency curve for the air charge inducted (full throttle).

All commercial forms of fuel injection pumps now in use utilize a plunger-barrel combination, as a pumping means. The type of injection pump in most extensive use at the present time, employs a port controlled icy-pass, with an undercut section of the plunger as the slide valve means for controlling the porting of this by-pass port in order to control the quantity of fuel delivered by the pump.

The following formula expresses the leakage rate of the above type of plunger-barrel pumps.

1. c is a constant.

2. Z is the mean clearance between the barrel or casing and the plunger.

3. d is the pump plunger diameter.

4. s .is the plunger velocity.

5. P is the pressure differential between the lapped portion between the plunger and the barrel.

6. [,L is the viscosity of the liquid being pumped.

7. L is the length of the lapped fit.

Due to the leakage condition it is necessary in this piston type of pump to provide a cam profile with a rate of lift sufiicient to overcome this leakage at slow speeds, especially cranking speeds as are encountered when cold-starting the engine. As a result, the speed-delivery characteristics of this type of pump tend to fall off at slow speeds (when the time for leakage is the greatest) and also at high speeds (when the pressure causing leakage is the greatest).

As a result of the above conditions the tendency at the higher throttle rack settings is to result in speed-delivery characteristics, which fall 01f much more rapidly with increasing engine speed than the volumetric efiiciency of the engine does, and results in the failure to maintain the air to fuel ratio.

As the throttle rack position is decreased, (smaller amounts per injection), the speed-delivery" characteristics continue to be altered until at the lower range of the throttle settings the curve has an exactly opposite slope. This condition is equally as undesirable as the former.

Thus it may be seen that as the quantity per injection at the higher throttle conditions falls off too rapidly due to leakage, there will be a speed at which delivery will fall below the quantities necessary, and result in a definite limit to engine speeds that can be obtained. This condition is especially bad when the high pressure pump and nozzle are separated by a delivery tube (due to adverse pressure wave characteristics).

In the modifications shown herein the efiect of leakage is eliminated by the use of a hermetically sealed pumping element, and a unitary construction is employed in order to overcome the disadvantage of a pump-delivery-tube-nozzle combination. The absence of leakage makes possible the use without adverse effects of what ever cam shape is necessary in order that the speed-delivery characteristics of the injector will conform exactly to the volumetric-efficiency curve of the engine. Thus in the modifications herein, it is possible to obtain complete and automatic load-speed control.

The injectors shown herein may readily be operated as pusher or sump pumps located at the source of supply and supplying fuel to injectors or a carburetor, also they may be used to inject liquid, as water, into the cylinders (or manifold) for anti-detonating purposes.

It is to be understood that I do not wish to be limited by the exact embodiments of the device shown, which are merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. In an injector, the combination of a housing having a pair of axially aligned chambers therein, one chamber being of larger diameter than the other, the smaller diameter chamber having a valve opening outwardly, resilient means urging said valve to closed position, a bellows secured at one end in said second chamber adjacent said valve, an intermediate seal movably disposed in said first chamber, the other end of said bellows being connected to said seal, a fixed seal spaced from said intermediate seal and fixed in said larger diameter chamber, an inner bellows fixed to said fixed and intermediate seals and communicating with said first bellows, an outer bellows fixed to said seals, an aligning sleeve between said bellows in said larger diameter chamber, means regulating the position of said sleeve to thereby regulate the relative movement of said bellows, fixed means for introducing fuel in said first and second bellows adjacent said valve, and a valve in said housing operated by said intermediate seal to permit exterior pressure to pulsate said outer bellows to thereby pulsate said other bellows causing fuel to be ejected from said first valve.

2. In an injector, the combination of a housing having a pair of axially aligned chambers therein, one chamber being of larger diameter than the other, the smaller diameter chamber having a valve opening outwardly, resilient means urging said valve to closed position, a bellows secured at one end in said second chamber adjacent said valve, an intermediate seal movably disposed in said first chamber, the other end of said bellows being connected to said seal, a fixed seal spaced from said intermediate seal and fixed in said larger diameter chamber, a member movable in said larger diameter chamber having means extending into said bellows for introducing fuel therein adjacent said valve, an inner bellows connected to said last named member and said intermediate seal and communicating with said first bellows, an outer bellows connected to said intermediate and fixed seals, valve controlled outlet means in said last named member permitting fuel to return and exhausting fluid from said inner bellows from a high point therein, means for regulating the movement of said last named member, and a valve in said housing operated by said intermediate seal to permit exterior pressure to pulsate said outer bellows to thereby pulsate said other bellows causing fuel to be ejected from said first valve.

3. In an injector, the combination of a housing having a pair of axially aligned chambers therein, one chamber being of larger diameter than the other, the smaller diameter chamber having a valve opening outwardly, resilient means urging said valve to closed position, a bellows secured at one end in said second chamber adjacent said valve, an intermediate seal movably disposed in said first chamber, the other end of said bellows being connected to said seal, a fixed seal spaced from said intermediate seal and fixed in said larger diameter chamber, an inner bellows fixed to said fixed and intermediate seals and communicating with said first bellows, an outer bellows fixed to said seals, means regulating the relative movement of th bellows, fixed means for introducing fuel in said first and second bellows adjacent said valve, and a valve in said housing operated by said intermediate seal to permit exterior pressure to pulsate said outer bellows to thereby pulsate said other bellows causing fuel to be ejected from said first valve, and means for supplying fluid pressure for pulsating said bellows.

4. In an injector, the combination of a housing, a valve opening outwardly of said housing, a bellows having one end secured in said housing adjacent said valve, an intermediate seal secured to the other end of said bellows and movable in said housing to pulsate said bellows, inner and outer bellows each secured at one end to said seal and at the other end within said housing, a throttle member movable axially of said housing, means between said throttle member and seal whereby movement of said throttle member regulates movement of said seal to thereby regulate the pulsation of said bellows, means for introducing pulsating fluid to said intermediate seal and outwardly of said first named bellows and the outer of said second named bellows, said last named means including a valve biased toward closed position but adapted to be opened by said intermediate seal, and means for introducing fluid to be ejected past said valve in said first named bellows adjacent said valve.

5. In an injector, the combination of a housing having a pair of axially aligned chambers, one

chamber being of larger diameter than the other, the smaller diameter chamber having an opening therein, a bellows secured at one end in said second chamber adjacent said opening, an intermediate seal movably disposed in said first chamber, the other end of said bellows being connected to said seal, a fixed seal spaced from said intermediate seal and fixed in said larger diameter chamber, an inner bellows fixed to said fixed and intermediate seals and communicating with said first bellows, an outer bellows fixed to said seals, an aligning sleeve between said bellows in said larger diameter chamber, means regulating the position of said sleeve to thereby regulate the relative movement of said bellows, fixed means for introducing fluid in said first and second bellows adjacent said opening, and a valve in said housing operated by said intermediate seal to permit pulsating pressure to pulsate said outer bellows to thereby pulsate said other bellows causing fluid to be ejected from said opening, and means for supplying fluid pressure for pulsating said bellows.

6. In an injector, the combination of a housing having an opening in one end, a bellows having one end secured in said housing adjacent said opening, an intermediate seal secured to the other end of said bellows and movable in said housing to pulsate said bellows, inner and outer bellows each secured at one end to said seal and at the other end within said housing, a throttle member movable axially of said housing, means between said throttle member and seal whereby movement of said throttle member regulates movement of said seal to thereby regulate the pulsation of said bellows, means for introducing pulsating fluid to said intermediate seal and outwardly of said first named bellows and the outer of said second named bellows, said last named means including a valve biased toward closed position but adapted to be opened by said intermediate seal, and means for introducing fluid to be ejected past said opening adjacent said valve.

WILLIAM H. MASHINTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,162,789 Loane, Jr. Dec. 7, 1915 1,425,191 Garbarini Aug. 8, 1922 1,455,628 Leroy May 15, 1923 1,856,852 Palisca May 3, 1932 1,976,415 Scott Oct. 9, 1934 2,046,491 Scott July 7, 1936 2,106,789 Boyd Feb. 1, 1938 2,180,128 Stanclifie Nov. 14, 1939 2,389,492 Edwards Nov. 20, 1945 FOREIGN PATENTS Number Country Date 264,787 Italy May 11, 1929 

